Segment Routing Traffic Engineering Commands

This chapter describes the commands used to configure and use Segment Routing Traffic Engineering (SR-TE).

To use commands of this module, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using any command, contact your AAA administrator for assistance.

affinity-map

To define an affinity map, use the affinity-map name name bit-position bit-position command in SR-TE sub-mode.

affinity-map name name bit-position bit-position

Syntax Description

name name

Specify the name of the affinity-map.
bit-position bit-position

Specify the bit position in the Extended Admin Group bitmask.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 7.3.1

This command was introduced.

Usage Guidelines

Configure affinity maps on the following routers:

  • Routers with interfaces that have an associated admin group attribute.

  • Routers that act as SR-TE head-ends for SR policies that include affinity constraints.

Examples

This example shows how to define an affinity map:

Router# configure
Router(config)# segment-routing
Router(config-sr)# traffic-eng
Router(config-sr-te)# affinity-map
Router(config-sr-te-affinity-map)# name RED bit-position 23

autoroute include ipv6 all

To enable IPv6 autoroute support for SR-TE policies with IPv4 endpoints, use the autoroute include ipv6 all command in the SR-TE policy and PCC profile modes. To disable this feature, use the no form of this command.

autoroute include ipv6 all

no autoroute include ipv6 all

Syntax Description

This command has no keywords or arguments.

Command Default

IPv6 autoroute support is disabled.

Command Modes

SR-TE policy

PCC profile

Command History

Release Modification

Release 7.5.4

This command was introduced.

Usage Guidelines

The include ipv6 all command form enables autoroute support for IPv6 prefixes, for a specified SR-TE policy. This command can be used in the SR-TE policy and PCC profile modes.

Examples

The following example shows how to configure the IPv6 autoroute function for an SR-TE policy with an IPv4 endpoint:

Router# configure
Router(config)# segment-routing traffic-eng policy pol12
Router(config-sr-te-policy)# autoroute include ipv6 all
Router(config-sr-te-policy)# commit

The following example shows how to configure the IPv6 autoroute function for a PCE-instantiated SR-TE policy with an IPv4 endpoint: 

Router# configure
Router(config)# segment-routing traffic-eng pcc profile 10
Router(config-pcc-prof)# autoroute include ipv6 all
Router(config-pcc-prof)# commit

bgp prefix-path-label ignore

To indicate BGP to ignore the programming of the service route’s prefix label when recursing onto the BSID of an SR-TE policy, use the bgp prefix-path-label ignore command in SR-TE policy steering config mode.

bgp prefix-path-label ignore

Syntax Description

This command has no keywords or arguments.

Command Default

None

Command Modes

SR-TE policy steering

Command History

Release Modification
Release 7.9.1

This command was introduced.

Usage Guidelines

This command can be configured for manual SR policies.

Examples

The following example shows how to configure BGP to ignore the programming of the service route’s prefix label when recursing onto the BSID of an SR-TE policy: 

Router(config)# segment-routing
Router(config-sr)# traffic-eng
Router(config-sr-te)# policy POLICY1
Router(config-sr-te-policy)# steering
Router(config-sr-te-policy-steering)# bgp prefix-path-label ignore

binding-sid

To specify the binding SID (BSID) allocation behavior, use the binding-sid command in SR-TE sub-mode.

binding-sid { dynamic disable | explicit { enforce-srlb | fallback-dynamic } }

Syntax Description

dynamic disable

Disables dynamic binding SID allocation. Candidate paths without an explicit BSID will be considered invalid.
explicit enforce-srlb

Specifies strict SRLB enforcement. If the BSID is not within the SRLB, the policy stays down.
explicitfallback-dynamic

Specifies that, if the BSID is not available, the BSID is allocated dynamically and the policy comes up.

Command Default

Binding SIDs are dynamically allocated

Command Modes

SR-TE configuration

Command History

Release Modification
Release 7.3.1

This command was introduced.

Usage Guidelines

Explicit BSIDs are allocated from the segment routing local block (SRLB) or the dynamic range of labels. A best-effort is made to request and obtain the BSID for the SR-TE policy. If requested BSID is not available (if it does not fall within the available SRLB or is already used by another application or SR-TE policy), the policy stays down.

This command specifies how the BSID allocation behaves if the BSID value is not available:

  • Fallback to dynamic allocation – If the BSID is not available, the BSID is allocated dynamically and the policy comes up.

  • Strict SRLB enforcement – If the BSID is not within the SRLB, the policy stays down.

Examples

This example shows how to configure an SR policy to use an explicit BSID of 1000. If the BSID is not available, the BSID is allocated dynamically and the policy comes up. 

Router# configure
Router(config)# segment-routing
Router(config-sr)# traffic-eng
Router(config-sr-te)# binding-sid explicit fallback-dynamic
Router(config-sr-te)# policy goo
Router(config-sr-te-policy)# binding-sid mpls 1000

distribute link-state (SRTE)

To enable reporting of SRTE policies, use the distribute link-state command in the SR-TE configuration mode.

distribute link-state [ report-candidate-path-inactive ]

Table 1. Syntax Description:

Syntax

Description
report-candidate-path-inactive

Enables reporting of SRTE policies using BGP-LS.

Command Default

The reporting of policies to BGP-LS is disabled by default.

Command Modes

SR-TE configuration (config-sr-te)

Command History

Release Modification
Release 24.1.1

Supports reporting of SR-TE policies using BGP- Link State for SRv6.
Release 7.10.1

This command was introduced and supports reporting of SR-TE policies using BGP- Link State for SR-MPLS.

Task ID

Task ID Operation

distribute link-state

write/read

Examples

This example shows how to enable BGP-LS reporting and syncing of SRTE Policies:


Router# config
Router(config)# segment-routing 
Router(config-sr)# traffic-eng
Router(config-sr-te)# distribute link-state
Router(config-sr-te-distribute-ls)# report-candidate-path-inactive
Router(config-sr-te-distribute-ls)# exit

distribute link-state

To enable reporting of SRTE policies, use the distribute link-state command in the SR-TE configuration mode.

distribute link-state [ report-candidate-path-inactive ]

Table 2. Syntax Description:

Syntax

Description
report-candidate-path-inactive

Enables reporting of SRTE policies using BGP-LS.

Command Default

The reporting of policies to BGP-LS is disabled by default.

Command Modes

SR-TE configuration (config-sr-te)

Command History

Release Modification
Release 24.1.1

Supports reporting of SR-TE policies using BGP- Link State for SRv6.
Release 7.10.1

This command was introduced and supports reporting of SR-TE policies using BGP- Link State for SR-MPLS.

Task ID

Task ID Operation

distribute link-state

write/read

Examples

This example shows how to enable BGP-LS reporting and syncing of SRTE Policies:


Router# config
Router(config)# segment-routing 
Router(config-sr)# traffic-eng
Router(config-sr-te)# distribute link-state
Router(config-sr-te-distribute-ls)# report-candidate-path-inactive
Router(config-sr-te-distribute-ls)# exit

hw-module profile cef sropt enable

To enable Segment Routing Encap object optimization, use the hw-module profile cef sropt enable command in XR Config mode.

hw-module profile cef sropt enable

Syntax Description

This command has no keywords or arguments.

Command Default

Segment Routing Encap object optimization is disabled.

Command Modes

XR Configuration

Command History

Release Modification
Release 7.5.4

This command was introduced.

Usage Guidelines

After you enter this command, you must reload the router.

Segment Routing Encap object optimization minimizes the Encap resource consumption of the forwarding ASIC. With this feature, instead of consuming an Encap entry for each outgoing path, the forwarding chain of a labeled prefix with ECMP consumes only a single global Encap entry.

SR Encap object optimization is triggered only when all ECMP paths of a labeled prefix (primary and backup) perform the same egress action (either all pop or all swap); and have the same outgoing label for the swap egress action. If this condition is not met, then the prefix is programmed with a dedicated Encap object per outgoing path.

SR Encap object optimization is supported for both labeled IPv4 /32 (SR-MPLSv4) and labeled IPv6 /128 (SR-MPLSv6).

All paths associated with the prefix (primary and backup) must have the same outgoing label value for SR Encap object optimization to be triggered. For example:

  • For prefixes with LFA backup paths, the SR Encap object optimization is triggered because these backup paths do not require an extra label to be pushed.

  • For prefixes with TI-LFA backup paths requiring extra labels to be pushed, the SR Encap object optimization is not triggered because all the paths associated with the prefix do not have the same outgoing label value.

Per-label per-interface egress counters are not supported when SR Encap object optimization is enabled. Instead, per-label aggregate egress counters are supported.

SR MicroLoop Avoidance is not supported when SR Encap object optimization is enabled.

Examples

This example shows how to enable Segment Routing Encap object optimization:

Router(config)# hw-module profile cef sropt enable

In order to activate/deactivate SROPT feature, you must manually reload the chassis/all line cards

Router(config)# commit
Router(config)# end

Router# reload location all
Proceed with reload? [confirm] y

Router# show hw-module profile cef

--------------------------------------------------------------
Knob                          Status          Applied   Action         
--------------------------------------------------------------
CBF Enable                    Unconfigured    N/A       None           
CBF forward-class-list        Unconfigured    N/A       None           
BGPLU                         Unconfigured    N/A       None           
LPTS ACL                      Unconfigured    N/A       None           
Dark Bandwidth                Unconfigured    N/A       None           
SR-OPT Enable                 Configured      Yes       None           
IP Redirect Punt              Unconfigured    N/A       None           
IPv6 Hop-limit Punt           Unconfigured    N/A       None           
MPLS Per Path Stats           Unconfigured    N/A       None           
Tunnel TTL Decrement          Unconfigured    N/A       None           
High-Scale No-LDP-Over-TE     Unconfigured    N/A       None           
Label over TE counters        Unconfigured    N/A       None           
Highscale LDPoTE No SRoTE     Unconfigured    N/A       None           
LPTS Pifib Entry Counters     Unconfigured    N/A       None

kshortest-paths

To set the maximum number of attempts for SRTE to compute paths that satisfy cumulative metric bounds criteria, use the kshortest-paths command in SR-TE configuration mode. To revert to the default number of attempts (100), use the no form of the command.

kshortest-paths max-attempts

no kshortest-paths

Syntax Description

max-attempts

Maximum number of attempts.

Choose a value between 1 and 200.

Command Default

100 attempts are made to compute paths that satisfy the cumulative metric bounds criteria.

Command Modes

SR-TE configuration (config-sr-te)

Command History

Release Modification
Release 7.3.1

This command was introduced.

Usage Guidelines

By default, a maximum of 100 attempts are made. To update the value, you can use this command.

You can use the show segment-routing traffic-eng policy color command (Number of K-shortest-paths field) to see the K-shortest path algorithm computation result. For example, if the Number of K-shortest-paths field displays 4, it means that the K-shortest path algorithm took 4 computations to find the right path. The 4 shortest paths that are computed using K-shortest path algorithm did not respect the cumulative bounds, and the fifth shortest path was valid against the bounds.

Examples

This example shows how to set the maximum number of attempts for computing paths that satisfy the cumulative metric bounds criteria: 

Router# configure terminal
Router(config)# segment-routing traffic-eng
Router(config-sr-te)# kshortest-paths 120
Router(config-sr-te)# commit

neighbor sr-policy name targeted

To configure the SR policy name under LDP, use the neighbor sr-policy name targeted command in SR-TE configuration mode.

neighbor sr-policy name targeted

Table 3. Syntax Description

Syntax

Description
name

Use the command to configure the SR policy name under LDP

name is the auto-generated SR policy name assigned by the router when creating an LDP targeted adjacency over an SR policy.

Note

 
You can use the show segment-routing traffic-eng policy command to display the auto generated SR policy name. Auto-generated SR policy name uses the following naming convention: srte_c_color_val_ep_endpoint-address . For example, srte_c_1000_ep_10.1.1.2.

Command Default

None

Command Modes

SR-TE configuration mode

Command History

Release Modification
Release 7.10.1

This command was introduced.

Examples

The following example shows how to configure the SR policy name under LDP:


Router(config)# mpls ldp
Router(config-ldp)# address-family ipv4
Router(config-ldp-af)# neighbor sr-policy srte_c_1000_ep_10.1.1.2 targeted  
Router(config-ldp-af)#commit

on-demand constraints


Note

From Cisco IOS XR Release 7.9.1, you must reconfigure all SR-ODN configurations with Flexible Algorithm constraints that use the on-demand dynamic sid-algorithm with this command.

To configure the SR Flexible Algorithm constraints, use the constraints segments sid-algorithm command in SR-TE sub-mode.

on-demand color color constraints { segments sid-algorithm algo | resources { exclude resource-list name | exclude-group group_name | apply-group group_name } }

Syntax Description

segments

Specify constraints for segments of a path in a network.
sid-algorithm algo

Specify the SR Flexible Algorithm value. The algo range is from 128 to 255.

resources

Specify resource constraints for path computation.

exclude

Exclude resources from path computation.

resource-list name

Specify the name of the resource-list to exclude from the path computation.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 24.1.1

The resources option was introduced.

Release 7.9.1

You must reconfigure all SR-ODN configurations with Flexible Algorithm constraints that use the on-demand dynamic sid-algorithm with this command.

Release 7.4.1

This command was introduced.

Usage Guidelines

No specific guidelines impact the use of this command.

Examples

The following example shows how to add an SR Flexible Algorithm constraint:

Router(config-sr-te-color)# constraints segments sid-algorithm 128

The following example shows how to associate the excluded IPv4 addresses for ODN SR-TE policies: 

Router(config)#segment-routing
Router(config-sr)#traffic-eng 
Router(config-sr-te)#on-demand color 7001
Routerconfig-sr-te-color)#constraints resources exclude resource-list node_resc_list

on-demand dynamic affinity sid-algorithm


Note

You must reconfigure all SR-ODN configurations with Flexible Algorithm constraints that use this command with the constraints segments sid-algorithm algo command.

To configure the SR Flexible Algorithm constraints, use the on-demand dynamic sid-algorithm command in SR-TE sub-mode.

on-demand color color dynamic sid-algorithm algo

Syntax Description

sid-algorithm algo

Specify the SR Flexible Algorithm value . The algo range is from 128 to 255.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 6.3.1

This command was introduced.
Release 7.4.1

This command was replaced by the constraints segments sid-algorithm algo command.

Release 7.9.1

You must reconfigure all SR-ODN configurations with Flexible Algorithm constraints that use this command with the constraints segments sid-algorithm algo command.

.

Usage Guidelines

This command was replaced by the constraints segments sid-algorithm algo command.

Examples

Router(config-sr-te-color-dyn)# sid-algorithm 128

on-demand dynamic affinity disjoint-path

To configure the disjoint-path constraints, use the on-demand dynamic disjoint-path command in SR-TE sub-mode.

on-demand color color dynamic disjoint-path group-id id type { link | node | srlg | srlg-node } [ { sub-id | | sub_id | fallback disable } ]

Syntax Description

group-id id

Specify the group ID of the disjoint path. Valid values are from 1 to 65535.
type {link | node | srlg | srlg-node }

Specify the type of disjointness.

sub-id id

Specify the sub-group ID of the disjoint path. Valid values are from 1 to 65535.

fallback disable

Disable all fallback behavior in case the requested disjointness cannot be achieved.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 24.1.1

The fallback disable keyword was introduced.

Release 6.3.1

This command was introduced.

Usage Guidelines

Configures the disjoint group ID and defines the preferred level of disjointness (the type of resources that should not be shared by the two paths):

  • link—Specifies that links are not shared on the computed paths.

  • node—Specifies that nodes are not shared on the computed paths.

  • srlg—Specifies that links with the same SRLG value are not shared on the computed paths

  • srlg-node—Specifies that SRLG and nodes are not shared on the computed paths.

If a pair of paths that meet the requested disjointness level cannot be found, then the paths will automatically fallback to a lower level:

  • If the requested disjointness level is SRLG or node, then link-disjoint paths will be computed.

  • If the requested disjointness level was link, or if the first fallback from SRLG or node disjointness failed, then the lists of segments encoding two shortest paths, without any disjointness constraint, will be computed.

Examples

Router(config-sr-te-color-dyn)# disjoint-path group-id 775 type link

The following example indicates how to configure strict disjointness for an ODN SR-TE policy:

Router(config)#segment-routing traffic-eng 
Router(config-sr-te)#on-demand color 4
Router(config-sr-te-color)#dynamic 
Router(config-sr-te-color-dyn)#disjoint-path group-id 1 type node fallback disable
Router(config-sr-te-color-dyn)#commit

on-demand maximum-sid-depth

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

on-demand source-address

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

on-demand steering

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

policy binding-sid

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

policy candidate-paths

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

policy candidate-paths constraints disjoint-path

To configure the disjoint-path constraints, use the on-demand dynamic disjoint-path command in SR-TE sub-mode.

policy policy candidate-paths preference preference constraints disjoint-path group-id id type { link | node | srlg | srlg-node } [ { sub-id | | sub_id | shortest-path | fallback disable } ]

Syntax Description

group-id id

Specify the group ID of the disjoint path. Valid values are from 1 to 65535.
type {link | node | srlg | srlg-node }

Specify the type of disjointness.

sub-id id

Specify the sub-group ID of the disjoint path. Valid values are from 1 to 65535.

shortest-path

Enable shortest path computation for the selected candidate path.

fallback disable

Disable all fallback behavior in case the requested disjointness cannot be achieved.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 24.1.1

The shortest-path and fallback disable keywords were introduced.

Release 6.3.1

This command was introduced.

Usage Guidelines

Configures the disjoint group ID and defines the preferred level of disjointness (the type of resources that should not be shared by the two paths):

  • link—Specifies that links are not shared on the computed paths.

  • node—Specifies that nodes are not shared on the computed paths.

  • srlg—Specifies that links with the same SRLG value are not shared on the computed paths

  • srlg-node—Specifies that SRLG and nodes are not shared on the computed paths.

If a pair of paths that meet the requested disjointness level cannot be found, then the paths will automatically fallback to a lower level:

  • If the requested disjointness level is SRLG or node, then link-disjoint paths will be computed.

  • If the requested disjointness level was link, or if the first fallback from SRLG or node disjointness failed, then the lists of segments encoding two shortest paths, without any disjointness constraint, will be computed.

Examples


Router(config-sr-te)# policy FOO
Router(config-sr-te-policy)# candidate-paths preference 100
Router(config-sr-te-poliilojkl,.cy-path-pref)# constraints disjoint-path group-id 775 type link

The following example indicates how to configure the shortest path preference for a disjoint path:

Router(config)#segment-routing traffic-eng
Router(config-sr-te)#policy dynamic_pcep_policy_disjoint
Router(config-sr-te-policy)#candidate-paths
Router(config-sr-te-policy-path)#preference 100
Router(config-sr-te-policy-path-pref)#constraints disjoint-path group-id 1 type link shortest-path

The following example indicates how to configure strict disjointness for a SR-TE policy:

Router(config)#segment-routing traffic-eng 
Router(config-sr-te)#policy foo 
Router(config-sr-te-policy)#color 1 end-point ipv4 10.10.10.1 
Router(config-sr-te-policy)#candidate-paths preference 100
Router(config-sr-te-policy-path-pref)#constraints disjoint-path group-id 1 type node fallback disable
Router(config-sr-te-policy-path-pref)#commit

policy candidate-paths constraints resources

To exclude IP addresses from the path computation for SR-TE policies, use the policy candidate-paths constraints resources command in the SR-TE configuration mode.

policy policy candidate-paths preference preference constraints resources { exclude resource-list name | exclude-group group_name | apply-group group_name }

Syntax Description

resources {exclude-group | exclude | apply-group}

Specify the resource constraints for path computation:

  • exclude. Excludes resources from the path computation.

  • exclude-group. Excludes the apply-group configuration from the group.

  • apply-group. Applies configuration from a group.

resource-list name

Specify the name of the resource-list to exclude from the path computation.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 24.1.1 This command was introduced.

Usage Guidelines

None.

Examples

The following example shows how to exclude a list of IPv4 addresses from the network resource list: 

Router(config)#segment-routing traffic-eng 
Router(config-sr-te)#resource-list node_resc_list 
Router(config-sr-te-rl)#index 1 ipv4 10.10.10.1 
Router(config-sr-te-rl)#index 2 ipv4 10.10.10.8

The following example shows how to associate the excluded IPv4 addresses to one or more candidate paths for SR-TE policies: 

Router(config)#segment-routing traffic-eng 
Router(config-sr-te)#policy dynamic_pcep_policy 
Router(config-sr-te-policy)#candidate-paths 
Router(config-sr-te-policy-path)#preference 100 
Router(config-sr-te-policy-path-pref)#constraints resources exclude resource-list node_resc_list

policy color

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

policy source-address

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

policy steering

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

resource-list

To configure a list of IPv4 addresses that you want to exclude from the network resource list for a candidate path, use the resource-list command in SR-TE configuration mode.

resource-list name index "1-65535" ipv4 ipv4-addr

Syntax Description

resource-list name

Specify the resource-list name to exclude from the path computation.
index 1-65535

Specify the index entry.

Ranges from 1–65535.
ipv4 ipv4-addr

Specify the IPv4 address that you want to exclude from the network resource list.

Command Default

None

Command Modes

SR-TE configuration mode

Command History

Release Modification
Release 24.1.1

This command was introduced.

Usage Guidelines

None.

Examples

The following example shows how to configure a list of IPv4 addresses that you want to exclude from the network resource list: 

Router(config)#segment-routing traffic-eng 
Router(config-sr-te)#resource-list node_resc_list 
Router(config-sr-te-rl)#index 1 ipv4 10.10.10.1 
Router(config-sr-te-rl)#index 2 ipv4 10.10.10.8

segment-list

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

separate-next-hop

To enable SR-TE with next-hop independent scaling optimization, use the separate-next-hop command in ST-TE configuration mode.

segment-routing traffic-eng separate-next-hop

This command has no keywords or arguments.

Command Default

None

Command Modes

SR-TE configuration

Command History

Release Modification
Release 7.3.1

This command was introduced.

Usage Guidelines

Examples

steering labeled-services

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples

te-latency

Syntax Description

Command Default

Command Modes

Command History

Release Modification

Usage Guidelines

Task ID

Task ID Operation

Examples